The backdoor cuts for layups were open for Northwestern last night. So were the killer three-pointers, set up with simple perimeter screens. Ohio State’s sense of help defense was absent, which was curious. We know they can defend. Did they forget?

It was a strange game played before an unsettled crowd of 15,842 in Value City Arena. This was supposed to be the one to put Ohio State back on track. It turned into a scare.

After losing an overtime thriller to No. 4 Michigan in Ann Arbor and getting schooled by No. 1 Indiana in their own gym, the Buckeyes had Northwestern — unranked and injury-

riddled — at home. Fans not privy to tickets for more-attractive games were dug in and ready to roar at something other than their television. They did a good job of goading the Buckeyes to victory.

No. 13 Ohio State went small, attacked on both ends of the floor, and ultimately drew away to a 69-59 victory. Sam Thompson provided the exclamation point with a couple of high-flying dunks, including a 360 that had Lenzelle Smith Jr. smiling as he backpedaled to set up on defense.

Give Northwestern credit. Coach Bill Carmody, pressed into starting two freshmen, installed a 2-3 zone to stave off foul trouble. The zone was shaded toward slowing Ohio State’s leading scorer, forward Deshaun Thomas. It worked for 30 minutes. Offensively, the Wildcats do what they normally do — which is run the clock down, lull a defense to sleep and then go all Pete Carril.

Thomas had five points through 20 minutes and seven points through 30 minutes. Northwestern had a 48-43 lead before a Thomas slam got him untracked. Credit the Buckeyes for maintaining their composure until they could assert themselves. They finished the game with a 12-2 run.

“We played well for 39 minutes,” Carmody said. “We were just trying to make it hard on Thomas, and if the other guys beat you, they beat you.”

That raises a good point about OSU (18-6, 8-4 Big Ten).

Northwestern (13-12, 4-8) is a scrappy lot and a handful for any opponent, especially if the game is in Evanston. Still, here were the Wildcats, on the road, with three-fifths of their opening-night lineup on the sideline, getting killed on the boards — and they were giving a ranked team fits. This game was winnable for them until the last 10 minutes.

Thomas needs help from somebody. This is not exactly a news flash, but it bears repeating. The Buckeyes are a hardworking, athletic and defensively demonic team, last night’s first half notwithstanding. But secondary scoring can be a problem.

Coach Thad Matta makes a fair point when he says that different players have made significant contributions of late, especially in the loss at Michigan. He notes that, in this game against Northwestern, four of his starters were in double figures.

“I wouldn’t say I’m concerned,” Matta said. “It has kind of been that way — I don’t want to say ‘hit or miss’ — but like tonight, Shannon (Scott) hit a huge three, Aaron (Craft) only had seven points, but he hit two of the biggest shots of the night, Sam had a huge three …”

It would be nice if Amir Williams’ low-post game suddenly materialized, or if LaQuinton Ross and Thompson were more consistent inside-outside threats, or if Craft shot for a higher percentage from downtown. The Buckeyes are 1-6 against ranked teams.

Thomas will need help the rest of the way. It is not chic to think the Buckeyes can win the Big Ten title, not after the Indiana slap-down — but it is all right there in front of them. They are in a three-way tie for third with six games left, including games against Wisconsin, Michigan State and Indiana.

“It’s strap it on and here we go on Sunday (at Wisconsin),” Matta said.

They are gritty — of that there is no doubt. We shall see now if it is enough.